I’ve seen a few with the “sash” vinyl top. Slant 6 cars also came with the black air cleaner lid. The 9” brakes sound like they got swapped out at some point. V8 cars came standard with 10” drums in 66.
It just looked like the 9 inch were on there from the beginning. I've heard that some might have switched brakes because they didn't like the discs, as they were fairly new, but I doubt they would have switched the rear 10 inch for 9s.
